Recent interest has focused on liquid crystal display devices of a horizontal electric field mode, such as an in-plane switching (IPS) mode and a fringe field switching (FFS) mode, which have excellent viewing angle characteristics. IPS-mode liquid crystal display devices have viewing angle characteristics superior to those of twisted-nematic-mode (TN-mode) and vertical-alignment-mode (VA-mode) liquid crystal display devices, as disclosed in Japanese Unexamined Patent Application Publication No. 2002-55341, for example. Such an advantage derives from the parallel alignment of liquid crystal molecules to the substrate of an IPS-mode or FFS-mode liquid crystal cell. Unfortunately, the liquid crystal molecules in the IPS-mode liquid crystal cell are not exactly parallel with the substrate, as disclosed in Japanese Unexamined Patent Application Publication Nos. 2002-55341 and 2004-94219. In specific, the long axes of the liquid crystal molecules are tilted in the thickness direction at a tilt angle (inclination angle) from the substrate, in particular, near the substrate surface. Such a tilted alignment of the liquid crystal molecules adversely affects the viewing angle characteristics.
Japanese Unexamined Patent Application Publication No. 2002-55341 discloses a birefringent film between a substrate of a liquid crystal cell and a polarizing plate, which has an optical anisotropy having the opposite sign to that of liquid crystal molecules in the liquid crystal cell and has an optical axis tilted in the same direction as the tilt angle of the liquid crystal molecules, to prevent light leakage when viewed from an oblique direction. Japanese Unexamined Patent Application Publication No. 2004-94219 discloses a positively birefringent material to prevent light leakage when viewed from an oblique direction.